Track release mechanism



Au. w, 1943.

E. F. NORELIUS TRACK RELEASE MECHANISM Filed July 26, 1940 4 Sheets-Sheet l Aug. 10, 1943.

E. F. NORELIUS TRACK RELEASE MECHANI SM Filed July 26, 1940 4 Sheets-Sheet 2 Aug. 10, 1943. E. F. NORE-IUS 2,326,486

TRACK RELEASE MECHANISM Filed July 26, 1940 4 Sheets-Sheet 3 J a u mg Aug. 10, 1943. E. F. NORELIUS TRACK RELEASE MECHANISM Filed July 26, 1940 4 Sheets-Sheet 4 cB/vW QMMA llll Mme/

'ing wheels.

Patented Aug. 10, 194

:5 iv a f TR KanigEAsE-MEcnAnrsM "Emil -F.-NoreliusfSpringficltl, assignor to Allis ChalmersManufacturing Company, Milwaukee, Wis., arcorporationielf Delaware t he Applica'tion JulylJZG, 1940, Serial No. 347,572,

'28 claims The invention relates to endless track vehicle and it is concerned more specifically with an improved track release mechanism for prevent; ingdamage to an 1 endless flexible track: belt and its supporting structure in case a rockor other solid obstruction: should become lodged betweenthe track belt and one of its support- In order to permit a rock or other solid obstruction to ,pass between the track belt and its supporting structure, it has heretofore been common practice to mount one of the track supporting wheels on a reciprocablelor swingable bearing and to -urge the bearing by means. of a resilient mechanism into a normal operating position, that is, into a position in whichthe mov ably mounted tracksupporting wheel, usually termed the track idler, is spaced from;the other track supporting wheel-a proper: distance to insure proper support of the track belt on mal operating position into a track releasing position, and to keep the track idleriand its-bear ingiin said normal operatingposition, as longas the track tension remains normal, but when the track tension becomes excessive due to a: solid obstruction being drawn between thef trackbelt and its supporting structure, the resilient mechanism yields and permits the bearing to move in track releasing direction. After; the obstruction has been cleared, the bearing is restoredto its normal operating position by the resilient mechanism. e

It is an object of the invention to provide a self-laying track-unit having an improved track both track supporting wheels during normal op- .eration of the self-laying track unit. The resilient mechanism operates to resist movement -of the track idler and-itsbearing from said nori the first part of the total travel allowedfor track releasing-movement of 'the bearingfi Such a co'r'r- *struction of the mechanism is desirable'because,

if an obstructio'n becomes lodged between the release mechanism of thementioned character,

that is,,a self-laying track ,unit in;which one of the supporting wheels for the track beltis' mounted on a frame for movement from a normal operating position into atrack releasing position,

and its support steadily increases asthe bearing movesin track releasing direction, anda's long as an obstruction remains lodgedbetweenthe track belt and its support such strain isjgreater'than that resulting from theinorrn'al track, tension.

It is another object ofthe inventionftol pro} vide an improved track release mechanisnrwhich willresist a certain permissible traclr tension' in excess of the normal track tension'wliile the re leasable track supporting. Wheel and its bearings are located at or near a n'ormal operatingip'osi tion, but which mechanism willpermit thetrack supporting wheel and'itsbearing to' recede from said normal operating position, or froma posi-'- tion in proximity thereto,'a substantial distance in a track releasing direction after the track tensio n*has exceeded the mentioned permissible amount, the resistance opposing 'suchreceding movement of the wheelandfbearing being not greater than the initial resistance against which, the'excessive tr'acl; tension is permitted tobuild up I V r e ore specifically, it is an objeet of the inven- -tion to provide an improvedtrack release mechanism of the mentioned character in'which the releasable track supporting wheel andiits bearing are subject to a relatively high initial resistance againstmovement in track releasing direction but are less forcibly opposed once said initial resistance-has been overcome and track re'leasing movement ofthe bearing has started. Prererably, the resistance is made to decrease during ftrack beltand its supporting structure, the track tenSion rises aboVe normal only'for a relatively 'shorttime, that is, until the obstruction has been drawn in between the track belt and itssu'p'por'ting structure far enough to move the bearing-"a V relatively short distancein track releasing direcand in which such movement of the supporting Wheel is controlled in an improvedmanner-by means of aresilient mechanism. I I

ln orcler to resist track releasing movement of the bearingvarious types of spring operated mechanisms have heretofore been suggested in which one or more initially compressed coil springs exert the necessary pressure for maintaining the track idler in normal position. Movement of the bearing in, track releasing direction causes further compression of the spring or springs, and if the rate of movement of the bearing equals the rate of compression of the spring,

has heretofore been usual in mechanisms of this type, the track tension increases in'rpro portion to the track'releasing trarel of the bearing. As a result, the strain upon thetrack belt tion. V e e i' Ajfur'ther object of the invention is to provide a spring'o'perated mechanism for producing the mentioned relatively high These and other objectaahd advantages ofthe invention will be apparent from the ,follOW-v k initial resistance againstmovement of the releasable track supring description of a preferred embodiment of the'invention. Referring to the drawings accompanying-and. forming part of this-specification, and in -.which'ilike reference :characters desig- A nate the same or similar parts in the several 'views: 11

Fig{ 1 is a side view of a crawler tractor em- -"'-of the"hub=ofthe idler l2 containing the roller ;hearings=l.4- ;and i=5. ;-The bracket 18 has a base 111)" portion-cof suhstantial length and width overbodying the invention; 1

Fig. 2 is a top view of ,thettractor shownrin Fig. 1, the track belt; at the leftasideof: the tractor being omitted to expose the trackrreleaee mechanism of theself-laying track unit at the left side of the tractor. A similar track release mechanism; not shown, is incorporated inithewselilayin trackunit at the right side. of the tractor;

311's an enlarged sectional view :of the mechanism for controlling movement or "the tnackwidlershown injigsjl an'd"2, theview being takendna splanetatfiri'ght anglesjtozthe axis of thelidl'errand showing the mechanisr'n'i'n'its normal-position; c V

.4.is La iviewesi milar 1m ,3, but showing the .mechanism in its extreme ltrack releasing i an enlarged section on, line V-'V "of Fig. k1,.showing.thetfrontidlenmounting;

,Eig..s6 .is aaside View -.0fa .bearinglsh'ownlin Figh-fl is a ,topview of the bearings shown in F n -16;

v ,8 a section. on; line VIIL-VIIL of. 71 showing a bearing; support withinthe; housing. .of the track release -mechanism; and

:9 --is .a sectionwon lineJlQ-IXof 3,

showing the gpivot mounting of i a, link within (the housing of the track release mechanism.

The tractor shown in .Figs. 1 and .2 -.comprises armainbodyrshowmin outline andrgenerally indireatedrbylthe'reference character .-and a pair dwelt-laying track units including ,trackbelts land :iatmppositesides:of-the minlbody A sprocket wheel 4 for. driving the track; belt zat rmimbody .-I :i-nthe usual manner .forrotation about a transverse shaft -5 at the ireareof .the main body, and :a r-similar sprocket -wheel .for

driving thetmckzbelt 3 at. the right side of the ,tractor ris irotatably mounted' on; the ,n ain 1 body eoaxml'ly zwlthmthej'spmsk'et' wmhe 50 A'thrust transmitting yoke 31" extends rear- .understood by those skilled in the-art. The 'driving sprockets {are drivingly -:connected with 1m: engine eat 4 the forwardend. of the vmain-both! A by the usual t-master gclutch, ,change speed .mechenism :-and steering clutches, which are.

conventionah elements of {the main -.body" and do .notsfornapariz\ofthist-invention.

The shaft 5 on which the sprocket wheelids imoimted has an outward extension, and. 1 our- ,neled on -said outward (extension of .the shaft .5

.israzbearing J! for connecting a ztrac'kirameat .the left side :of the tractor to the rear of .the

rmainbody. lIhe track-frame. comprises an, outer.

hto leave an unobstructed :space lbetweenvthe. for- 7 award ends ofthelinner and outer channellirons .18 andia, fortmounting ofafront idlerlZ.

Referring to Fig. 5, it willbe seen that the gfront idler J2 is,rotatably mounted on .a. shaft [.13 :hy means of two \conical roller bearings 1.4 and IS, the inner races of the roller bearings Y abutting against flanges IS on the shaft and A the outer races being engaged by bearing retainterse Hssecuredlto the hubcoftthe idler wheel l2. Tress-fitted upon oppofite en'ds of thesshaft l3 5 are two brackets l8 and I9, and'rotary seals 20 and 22 are interposed between the brackets and the bearing retainers to seal the interior space 23 extends downwardly from the bracket l8 adjacentto the inner sitie-ofthe channel iron 8, anda--shoulder fl"extends downwardly 'from the bracket= I 9'-adjaeent=to the inner'side'of the chan- "nel iron 9 to -retain the front idler assembly against displacementtransverselyof *the track frame. entire-'front id'lfer assembly,-including"the idler Wheel fl sha-ft F3, "and: brackets" I8 and I9, is slidable as a unit longitudinally of the track framefthe base portions'of the brack- 5 ets PS -and F9 having smooth hoiiz'ontal 'bottom surfaces slidably bearing upon the smo0th=horizontal top surfaces-- of the upper flanges of the channel =irons 8 and "9, respectively. blockfl secured to the bracket [8* projects under the top-fiange'of thechannelirohflgandanother i block 721 projects under the-"top flange of thechannel iron 9" to keep the idler assembly and track frametogether-vertically. {In addition to the; shaft" l3, the-bracket 1 8 carries a guard -18 (Fig. 5-) "forithe idler wheel' P2, the guard "being secured-to the bracket i [-8 at forward 'and rearward shoulders 29' and '30 "thereof, the for- Warrishoulder 29 extemiin'g upwardly from the "base ofthe bracket in front of a central barrel 4 0 portion 322Whieh surrounds'='the-='shaft l3, and

5 -*Anotheridler. guard corresponding to the icl-ler guaifiififigfi) is -secured to=the br-acket [9 at forward and rearward shoulders 34 and 35 fthe'reofcorresponding. to the forward an'd' rearward shoulders 29" and 30- of the bracket l8.

wardly from the frontidler assembly'an'd-has ftw o legs at opposite -sides,'respectively,-of the idler wheel 4'2,=one-ofthelegs-being-secured to the rearward shoulder 30' of the bracket 'Hlby -g5-meansof two 'bolts -38, and'the otherleg of the joke being similarly secured --to the rearward shoulder 35 ofthe bracket l 9. Formed integrally with*the-bridgeportion of the-yoke is a rearwardly-extending sleeve which is split at'BSl-and o "has a horizontalthreaded" bore 'for the reception of an adjustingscrewdfl. The-adjustingscrew has'a rearward polygonalshoulderl! for turning it withinthe threaded 'bore of the 'yoke, and the sleeveportion'of the yoke "has a pair of lugs 5 through'whichextendtwo'clamping bolts 43 for securing the-screw against turningin anyadjusted position. A semi-spherical head :44 is formed on the screw40,'forwardly of the shoulder l2 ,'for cooperation with a cross .head 45 forming art of a spring controlle'd mechanism for re- ;sisting. rearwardisliding movement of the idler 'assem'bly'on the 'trackframe, and'which mechanism is constructed as follows:

Mounted .on the portion of the track frame "IBIwnicn extends between the rear sprocket wheel serene Y straightlink 61.; Them end ofthelink s1 is. embraced bythe forked end 'of an arched link 68 to whichlthe link 61" is pivotally'secured by means of a pinBSJ The arched linkBB ispivotally V rad j rb tj d e '2: i5 h s n h c s secured to the top flange of thechanhel 'iron- 8 by a series ofbolts 59 a'nd to the top flange got the channel iron "9 by'a serie'sof bolts 60, as shown in Figs l and 2. 1A bottom wa ll 56 ofthe housing l'l merges with upwardly'coriverging side walls 49 and 50 as shown in Fig.9;theside'walls extending throughout the length of the housing longitudinally of the track frame, but the bottom wall 56 being of shorter-length," as shown in Fig. 3, and merging atits forwardv end with a transverse web 6| between the sidewalls 49 and 50, and

at its rear end with an internal 'flange 5| of the housing; A top opening of the housing affords access to the interior space between the web BI and the flange 5!, the top opening being normally closed by a cover 54. A vertical front wall 48 extends transversely between the side walls 4'9 and Si! in advance of the web 6|, the latter merging with a boss 53 which extends rearwardly from' the front wall 48. The boss 63 merges with a transverse top portion 52 of the housing and has a cylindrical bore, 62 in it, the bore ac commodating a cylindrical portion of the cross head 45 which is slidably fitted into the bore 52 for reciprocating movement longitudinally of the track frame] f V The sidewalls 49 and 5%, as indicated, continue rearwardly beyond the plane of the internal flange 5 I, and in rear ofthe flange 5| the housing 41 has a horizontallyextendingftubular rear portion which 'is interposed -between andmerges with the side walls 49 and 58. The upper half of the tubular rear portion forms an upwardly curvedtop wall'hfi of the housing which connects the sidewalls 49 and o'flj while the'lower half of the tubular rear portion extends into the space between the-side'walls' liland 56 in rear of theflange 5|. -The tubularrear portion has a 'circumferentially continuous inner cylindrical surface ligand it is closed at the rear ofthe housing by a cover bolts 8! extending through the cover and into a flange at the rear end of the housing to secure the cover 55 in places The portions of the side walls 49" and 5!! at opposite sides of the rearward tubularportion ofjthe housing 4'! have outwardly extending bottom flanges El and 58, respectively, as shown in Figs.

'1, '2 and 9, the "flange 51 having holes for'the reception of the fastening bolts 59, and the flange 58 having holes for the'reception'of the fastening bolts Similar flanges 'andfastening bolts are provided at the forward portion of the housing 43, as may be seen'from Figs. 1 and 2.

The semi-spherical head 44 ofthe-adjusting screw 50 bears upon a semi-spherical recess in a forward cylindrical portion of the cross head '45,

said forward portion of the cross head being of smaller diameter than the socketed cylindrical portion which is fitted into the bore 62, so that the outer surface of the forward cylindrical portionof the cross head will not come in contact with the surface of the bore 62-when the cross head movesback into the housing upon track releasing movement of the idler assembly. A seal ring 54 is mounted in. a circumferential groove of the portion of the cross head which slides within the bore 62, in order to prevent the ingress of foreign matter into the housing and the escape of lubricant therefrom.

. The portion of the cross head '45 which slides within the bore 62 has'a forwardly tapering conical recess 65 coaxial with the screw 40, and the forward end of the recess 85 is rounded to form a spherical seating surface for the ball head of a inwardly from the side walls 49 and 5E), respecbearijngsupport 14 which isformed integrally tively, of the housingA'L- 'Thepinbosses l2 and l3 a'reloc'ated in rear of a:transverse tubularwiththe housing 41, and which bearing support encloses the outer arm of a stabilizing crank 15.; V The inner arm of the stabilizing crank is mounted on the main body I of the tractor by means of .a fore and aft swingable bearing l'l,.,shown in i Fig. 8,- the purpose of the stabilizingcrank-being,

. to retain the track frameagainst t'oeing in. or

'noted that the links 61 and as form twoarms i pivot pin 69 is slightly spaced fromytheda'sh 1 out and against lateral tilting relative to the main body of the tractor in a well-known manner. For a more detailed description of the function of the stabilizing crank reference is here made to U. S. Patent 2,049,858, August 4, 1936,

E. F. Norelius and Yount, Tractor frame suspension.

The tubular bearing support 14 has a stop lug 18 at its upper portion underlying the arched link 58, and another stop lug I9 is formed on the arched portion of the link 68 overlying the tubular bearing support 14, the lug '19 being" adapted to engage the'lug for the purpose oflimiting forward swinging movement of the link 68 on the pivot pin 10. Referring to Fig. 3, it-will be of a toggle which reacts between the track frame and the cross head 45,and that the-axis of the dotted line AA, which represents a plane through the pivot axis of the linked on the track frame at H1 and through the pivot axis of the link 61 on the cross head 45. vIn other words, in the position of the links 61 and 68 shown in Fig. 3 the toggle occupies a moderately broken position, and the toggle is prevented from moving into its dead center position by the engagement of the lug 19 with lug 18. v

Enclosed within the tubular rear-ward portion of the housing 47 and surrounded by the cylin a I drical surface H is a heavy coil spring 32 which has a flattened rear' end abutting against the cover 55. The front end of the spring BZ'islikewise flattened and bears against a spring plunger 83 which is movable back and forth on the cylindrical surface H. The plunger 83 has a central rearwardly tapering conical recess 84, and the rear end of the recess 84 is rounded to form a spherical seating surfacefor the ball head'of a link 85, 'I'he front end of the link 85 is embraced'by a forked portion of the arched link 68 towhich'the link 35 is pivotally secured by means 7 o'fia pin Bl. r

In the positionflof the mechanism shown a in Fig. 3, which isthe normal operating position of the mechanism, the coil spring 82 exerts a substantial forward pressure upon. the spring plung er 83, which pressure is transmitted to the arched link 58 by the link 85 and which pressureis taken up by the-tubular bearing support 54 due to en-- gage'ment of the lug 19 with the lug '55. The precompression of the spring BZ required to produce the mentioned pressure may be obtained" by screwing hometh'e bolts Bl which retain the rear f cover 55 on the housing 4?, and which'forthat purpose are-of relatively great length. 'The portion ofthe linkfis which extends between the pivot :pins 111 and 81 con stitutes 'one arm of a second-toggle whose other arm is formed by the link 85, and which-second toggle reacts between the secondtoggle occupies a substantially broken position. v

Asshown in Fig. 1, the'track belt '2 is trained over the rear sprocket wheel 4 and the front idler wheel l2,'both of which wheels act to. support the trackbelt, andaseries .oftruck rollers 88 which are mounted on the track frame bear upon the ground run of thetrack belt in the usual manner. The weight of the main body is sustained onthe' frames of the right and left track units by from and'rear connections which are also 'of conventional construction, the' track frames being pivoted on the main body coaxially with'the rear. sprocket wheels, and the forward portion of the mainbody being sustainedon the track frames by means of a transverse leaf spring 89, indicated in Figs 1 and 2. A roller 98 is mounted'on the top cover of the housing 41 to support the upper run-of the track belt.

agas-ea ing structure. occupy jheir' normal operatingposition is definitely and accurately determined 7 normal position of themechanism, as shown in Figs. 1 and 2 show thefrontidler i2 and its bearing structure in their normal operating position,- that is, in the position which the front idler the track belt would then be liable to jumpcfi at the front idler IE or the rear sprocket wheel 4. In the mentioned normal operating position of the front idler l2'and its-bearing structure the frontidler is spaced from the rear sprocket wheel [the correct distance whichit mustjbe spaced from said sprocket wheel in order to avoid excessive slack of the track belt and atthe' same time leave enough slack in it to enable the links of the track belt to ride smoothly around the front idler'and the rear sprocket wheel.

It should further be noted" that under normal operating conditions ofthe tractor the front idler l2 and its bearing structure are subject to forces which tend to move the front idler and its bearing structure longitudinally of the track frame towards the rear sprocket wheel 4, said forces resulting primarily from the weight of the upper run of the track belt 2.-

Fig. 3 shows the toggle mechanisms within the housing 4'! in their normal position, which normal position of the toggle mechanisms,- corresponds to the mentioned normal operating position of the front idler I2 andits bearing structure as shown in Figs. 1 and 2. It will be noted that-in thenormal' position of :the toggle mecha- -nisms the arched link 68is subject to pressure by the coil spring 82 due to the mentioned precompression of said spring, and that the position .i-nto whichthe link 68 is normally urged under said pressure while-the front. idler'and its bear- Fig. 3, the toggle links 61 and '68 are located fairly closeto their dead center position, and, as stated hereinbefore, the coil spring'82 is precompressed and strongly resists movement of the toggle links .6! and 58 from their moderately broken positioninto a more completely broken position. Consequently, the cross head 45 will be capable of withstandinga considerable rearward thrust without starting to move in a. rearward direction and the backward-pressure to which the cross head 45 must be subjected in order to lift the toggle link 68 from. the stop lug 18 is several times higher than the rearward pressure upon the cross head resulting from the mentioned rearward forces which normally act upon thefront idler l 2 and its bearing structure. The normal-working position of the-frontidler l2 and its bearing structure may -be adjusted without disturbing the normal position of the toggle mechanisms as shown in Fig. 3, by turningthe adjusting screw 40.

Supposing now that a solid rock'lodges itself on the lower run of the track belt in advance of the sprocket wheel 4,-and.that the rock is small enough to enter between the-track rails -92*and to'drop between-two ofthe hinge pins 83. As the tractor advances,-the clogged up portion of the trackbelt will come into contact with the sprocket wheel 4 and one'of the teeth oi -the sprocket wheel will hit the rock and be preventedfrom entering the space which is clogged-111p by the rock. Asa result, the tracktension will increase beyond normal and develop-an additional tack pressure upon the idler wheel l2. Such back pressure istransmitted through the idler shaft [3, the roller bearings [4,15, brackets l8, 1 9, yoke 31, and screw 40 to the-cross head 45,'and

at the cross head the backpressurewill be re-- sisted by the toggle links 61 and 68. As the clog gedup portion of the track belt rides up on the sprocket wheel 4, the backpressure upon the cross head increases and reaches a point where thepressure of thecoil spring 82 is insufiicient'to keep the arched toggle link 68 against the stop lug 18. The toggle 61, 68 then starts to recede into a more completely broken position while'the spring plunger 83 is forced back against the pressure of the coil spring and the compression-of the'latter increases.

It will be noted that the toggle 5'1, 68 rapidly develops a mechanicaladvantage over the pressure of the spring 82 as the arched link '68 swings ba'ckon the pivot pin 10, and that at the same time the second toggle formed by the link 68, andthelink 85 is moved from its substantially broken position towards its dead centeriposition. The straightening movement of the second toggle produces a further'mechanical advantage over the pressure'of the spring 82, and as a result of the combined mechanical advantages produced by the firsttoggle 61,--68 and the second toggle 67, 85, the resistance opposingbackward movement of the cross headlidecreases as'the cross lieved from said increased stresses. The track re- I limits thebackward movement of the cross .head v head 45 proceeds ina rearward ortrack releasing sistance opposing backward movement of the cross head '45 starts dropping immediately as soon as the cross head beginsto move rearward y,- V and that a relatively short rearwardtravel of the cross head which is only a'smallfractionfof' the total rearward movementof which it is capable, reduces the opposing resistanceto less than half of the initial resistancewhichj'mustbe overe.

movement in a rearward or track releasing'direc non; After the initial rapid decrease of the .op-' posing resistance, continued I backward travelfojf the plunger 83 causes a. further decreaseojf'the opposing resistance," but atfa slower rate than. during the first small fraction "of its rearward movement. Inasmuch as the resistance opposing rearward -movement of. the idler l2 decreases substantially during a'relatively short rearward travel of the idler, all parts of thefseli-laying .track unit; which become subject to increased stresses. due to the entry of an obstruction be tween thetrack rails or otherwise, are quickly'release mechanism embodying the invention therefore reduces the, danger of breakage of the stressed parts and tends to prolong the life'of the self-laying track unit! After the clogged up portion of the track belt leaves the sprocketiwheel 4 atthe upper run of the track belt the spring 82 .actuates the, toggle 6 8, 85 andfthetoggle fili'l to move the front idler l2 and its bearing structure back into their'normalworking position in which they are shown in'FigS; land 2.

A pipe 94 abutting against therear spring 82 provides a stop for limitingibackward movement of the spring plunger 83 which inturn 45 and of the front idler assembly. Fig; 4 shows .the mechanism in its. extreme track releasing position, and it will be n'otedfrom a comparison ofFig. 4 with Fig. 3,that in the extreme track releasing position the first toggle 61; 68 has been moved from] the moderately brokenfposition 7 shown in Fig.3 into a more completely broken position, while the second toggle'68j85 has been moved from the substantially broken position shownin Fig. 3 towards its dead center'position.

For purposes'of identification, the arched link 68 constitutes a first link or an arm, thelinks fil and 85 constitute a' second link a third link,

respectively, and the cross head 45 and the spring plunger'83 constitute a-first and a second reciprocable" support or elementrespectively.

"The initial position of the togglejrnechanisrns,

1 as shown in Fig. 3, is determinediby' engagement of the stop 19 with the stop 18, and"asf'stated hereinbefo're, the 'stop 18 alsoj-takes upthe'jload' of the springBZ which is'initially tensioned, As

shown in Fig. 4, engagement of the plungerlil withthe tube '94 determines the final position 7 of the togglemechanisms and'limits' the deflec--- tion of the spring 82.v Control of the toggle mechanisms and of the' spring 82'is therefore efiected by means including the tubeor 'stop 94 which is engageable by the plunger 83, or more I generallystated, by means including a stop on ewe corneby the cross head in order to; initiatefits" the reciprooable elements .45; 83'. The thrust transmitting 370K831 between the'fiont idler l2 and the cross head 65,

eachother, namely, by' rotation of the sci-swim 12 'relative to the arm 68-,o'r more specifically stated, to adjust the axis of the front idler relative to the cross h'ea'dei, and while such adjust t have pivotal thrust con- 'nections, respectively, with thecross head 45 and V with the spring. mungeraa rhe forwardlyjta perin'g "conical recess fieof the cross headfi45-and 1 the ball'hea'd of'the link B'liconstitute'a-socket "and'a thrust 'element respectively',"which bear upon each other in thrust transmitting direction Qandare freely separable from each other irrth'e opposite direction; Similarly, the'frearwardly tapering conical recess '84 of the plunger-83"and ,the f ball head of the-link 85 constitute a socket a'nda thrust element'bearinguponeach other 7 Q in thrust-transmitting direction and ireelysep arable from each other -in-the opposite direction.

J The freely separable sockets andthru'st elements .facilitate installation of the spring 'an d xtoggle mechanisms within and their 'remov'al-from the .h g 4" f I y 7- f .i Y

The

within wide; limits by changing the proportions of the toggle links and-"theinrelative arrangement; For instance, it will be noted that the -linki6flis connected-to'the archedlink EBat a fpi n'flo than the link- 85. "Thegproportioning of. fthes'eradialfdistances and the angular relation existing condit'ions amirequirements. 1

mechanism and the coil *spring are enclosedfin a' compaet housing 4'! which is closed on all sides so that it canbe filled with lubricant, the cross head 4fi'having' a seal ring 64,,asfstated, to -prevent'the escape of lubricantthroughthe bore' 62, and :the jcovers 5.4 and f55ffpreventing escape of lubricant atthe top opening and at the rear opening of the'housingi. A's' shown. in Fig.1, an 'openiiigjat the side ofthe housing is-clos'ed by a 'p'lug '95 which maybe removed inorder to f iillthehousing '41 with lubricant to a substantial While n the foregoing, "a preferred embbdistructionherein' shown and desc "bed," for various ,modifications within the scope fthe appended Patent;

f 11m 3 S mnying track m na e-a rmail,- a track supporting wheel and "a 'bearin'g therefor movable iroma normal"operatingpositionon said .75. irame intojatrack releasing position, ar'e'cip'io a;

. I a a 5 the track framawhich is engageable by one of 7 and the ad-g j'ustin'g screw 40 are parts ofa thrust connection :and they are'extensibly adjustablerre1ative to within the threaded sleeve portion'oi the yoke 31 after loosening of -the':bolts 43. Rotation of the screw 40 isefiective to adjust the front idler functioniof the track release-mechanism a Am-herein shown-and described; may be, modified cover 55 of the housing 47 and extending within the. coil l on ger r radialj distance from thefaxis of the pivot fthe pins Bil and 81' 'may'be' selected to meet It should a ls'o" be noted that the entire uni? m ntjof' theinvention" nae been disclosed, it should bejunderstood thatit 'is not intended to liinit-ithe invention to the exact; details of con- 2 fclairn's may occur'fto' persons skilledfin the: artl .Itiis claimed and desired t [secure by'Letters 1 v releasing'p'o'sition.

ble support operativ i e ts with said ha ing, a toggle mechanism comprising a firstlink pivoted on said frame, a second link pivoted" on said supportv and a common pivotal connection between said linksat such distances, respectively,

irom the pivot axis of said firs't'link on said frame and from the pivot axis "of said secondlink on said support that said toggle, mechanism may occupy a moderately broken position while said bearing occupies said normal operating position, and resilient means ope'ratively connectedwith said toggle mechanism to yieldingly resist move V 'ment thereof from said moderately broken posi-v tion into a more completelybroken position due to movement of said bearing from said normal operating position into said track releasing posit onsaid-frame intoa track releasing position, a reciprocable support operatively comlectedvvith said bearing a, tog le mechanism comprising a first link pivot e dgon said f r ame,faljsecond" pivoted'on said support and, a common pivotal connection between said links at such distances, respectively, from the pivot axis of said first link on said frame and; from -the pivot'axis of said second link on said support that said toggle 1 30 andiwith said other re'ci mechanism may occupy a moderately broken position while said bearing occupies said normal 7 a in q i iea and in m n e in against said irameand operatively connected with said first link at a fixedvradial dist ance'from the pivot. axis of :said-firstlink on said f rame to yieldingly resistfmovement of said toggle mechanism from said moderately broken positioninto V .am comp e l b ok n p sii o i i b-i l i 'ment of said bearing fromsaidnormaloperating y e to 40 Vating positi'onflinto said track; releasing position.

position into said track releasing position: 1" I v 3. a 'self -layin 'g-traok'mechanism a frame, a track supporting wheel and abearingtherefore movable from a normal operating positionon said frame into a track releasing position; a reciprocable support ,operatively'eonneoted"with said heating, a, togglemechanism comprising a 'nrst mk pivoted on said frame, a second link'piVoted n said support a common-pivotalconnection between said links at suchdistances, respectively,

from the pivot axis of said first link .on said frame and from the pivot axis of said'secondflink on said support that said toggle mecnanisni may occupy a moderately broken position while; said bearing occupies said normal operating position 4 and spring means reacting against said frame and operatively connected with said firstilink gat at a radial distance from 'the pivot axis of aid first link on said frame,; which is shorter than the radial spacmg p: the pivot axis of said common pivotal connection from said pivotaxiseoi said first link on said frame; "said spring means being effective to 'yieldingly resist movement of' said toggle mechanism' from said moderately j "brokenpositionfinto aimore completelybrf 'e'n j :fpcsiti'on due; to movement or said 'be'ar'ing "rrem =60 said normal operating position 'i'nt'o' said] track 41111 a selflayingftrack mac ini ts, a ast;

a track supporting "wheeianda bearingfthe'ief 't' movable'from a normal operating "position. onsaid frame into a track releasing position; a reciprocable support operatively' 'connectediwith'said,b'earing; a first, toggle.- mechanism comprising a pair of linksjrespectivlyjfpivoted on said Iramejaiidi nnfsaid support another support reciprocably" ted on saijd triaineia rs condjto gle mecha} Iiism 'op rativelyj connect n f aid fi f t, og l mchani fw h, a d'bthe s pport; one iof said lo ndie i see aweaman: on aid supp r at.'i a d'firs qselemec anism "'25 q i u a mode at oken position while said earin ccup e ".s idln r nal perat n position; another reciprocabl support mounted on tive'l y elonnected With said n S d f m s n tcss ame han sm o erarst'toggle mechanism a a e uimrt whe b 'movement ,of said first jtojg'gle" mechanism from said moderately brokenposit'ion intol a more com- 'D tej1y roken positionfdue .tq rack, leas n QYfim mfiiifs'aid' b rinajwiiimove s i s c n 1 s' itionlto wards' its dead center position, and resil- Vient 'ineansrea'cting' between said frame and said rigthertreciprocaole {support tog yieldingly resist movement of'sald bearing fIOmZS aidIlQlIIlaI jope'i- 6. IniaJselHayingJ-rack.mechanism,fa frame, a track supporting vheelja'nd a bearing therefor movable fromf a" normal; operating position on ffsa'idjframe in-to a tra'cl releasing .positi-on a first '45 reciprocable support j 'o-iieratively 7 connected, with said bearing; a' first toggleimechanismfjcompris "ingaffirst link fpivoted onbsaid \frameja second r p jotal con'nectionbe'tween 'saidffirst and second 00 "links fat suich .distano'esg respectively,. from ,the gpwmfansior saidlnrst link o said framerand g mme at-Pi t:ax s-.Qfe eid e d link 0 said fir st support that said first toggle mechanism ma 1 9? amPd rei lY' V-b'mk n i t on While idrb tias;q aeisss isi n r Operating posit az sse e 'i eb vbe r a m said frame, at'second togglemechanism .comprisling a trn cylirik {pivoted pageant secon sl1pport -l e ti n @Wshsflfifst an third 1111115: 11 distances, respectively, Irom San ljfirst 2li kjoii said frame vot" axis lofisaid thnid link on at vsai second toggle mechfsaid; 'modera ely Br ,ne n reacting betiveengsaid frame and :saidsecu port-to yieldin'glyf sist lmbVement of-said 7O second toggle mechanism'tfromjsaid substantially j broken positionftliereof towards. its dead. center position. due] to 'gincveqint offsaid t first toggle mechanismi fiomisaid. moderately; broken posi- I. tion int:o a lrnorelcompletely.gbrokeniposition. by 75 movementof said bearin from its normal oppivotedfon saidffirstgsu port and a common I iupy a substantially brokenz osiv oggle ,mechanisn joecupies position and resilient crating position into said track 7 releasing" posi tion. 1

7; In a self-laying track mechanism; a frame, a track supporting wheel and a bearing therefor movable from a normal operating position on said frame into a track releasing position, a first link mounted on said frame for pivotal movement relative thereto about a first axis, a second link pivotally connected with said first link on a second axis spaced from said-first axisjn'ueans ineluding a reciprocable support operativelycon nectedwith said-bearing and pivotally connected with said second link on a third axis spaced from said second axis,-- whereby said third axisin the position thereof corresponding tofsaid normal operating position of said bearing 'will be spaced from said first axis'soas' to locate said second axis in relatively close proximity to a 'plane through said first and'thirdaxes, at-one side thereof, and whereby movement of said bearing from said normal operating position into said track releasing positionwill'causesaid second axis to'recede from saidplane at said'one side thereof, means for preventing approach of said second axis towards said plane? at said "one side thereof, beyond said positionof relativeiy close proximity thereto, and-pressure means operatively connected with said links-to resiliently resist saidreceding movement of said second axis from saidplane, J

8. In a self-laying track mechanism, a frame, a track supporting Wheel and-a bearing therefor movable from a normal operating positionfon said frame into a-trackreleasing position, a first link mounted on saidframe for pivotal movement thereof,-and whereby movement of said bearing from said: normal operating position into said track releasingpositionwill cause said second axis to recede from said plane atsaid one side thereof, and spring means reacting against said frame and operatively connected with said first link to resiliently resist s'aidreceding movement of said second axis, said first linkhaving a portion engageable with a stop on said track frame to prevent approach of said second axis towards said plane, at said one side thereof, beyond said position .of relatively'close 'proxiiriity of-said seoondaXis toisaid plane. j j I a 9. In a self-laying track mechanism, a" frame extending in the direction of propulsion of the mechanism, a track supporting Wheel and a bearing therefor mounted at one end'ofsaid frame'for movement longitudinally thereof, a spring abut ment mounted on said frame in "spaced relation to said bearing, a coil spring seated at one end on said abutment and extending longitudinally of saidframe towards said bearing, a plunger engaged by-the other end of: said coil spring, a first link pivoted on said frame in the space'be tween *said spring'abutment and saidbearing,

a cross head mounted on -said frame "formove "men-t longitudinally thereof in the space between the pivot axis of said first link and saidbearing,

with said plunger, and a thrusttransmitting con- 'nection between said cross headand said 'bearing. a I Y extending in'the direction of propulsion of the mechanism, a track supporting wheel and a bearing therefor mounted-at one end of said frame for movement longitudinally ther'eof, a-springabutment mounted on-said frame in spaced rela tion to said bearing' a-coilspring seated at one end on said abutment and extending longitudinally of said frame towards said bearing, a plunger engaged by the other end of said coil spring, afirst" link pivoted on said frame in the space between said spring abutment and-said bearing, across head mounted on said frame for movement longitudinally thereof in the space between the pivot axisof said first link and said-bearing,

fasecond link connecting-said first link withsaid cross head, a third link connecting said first link with said plunger, relativel'ystationary and movable stop elements associated, respectively, with said frame andwith said firstlink and engage-- able with each-otherto li-mit movement of said firstlink by movement of said 'plunger,said coil spring being compressed to urgelsaid movable stop element into engagement with-said station'-- ary stop element, and anextensible thrust trans mitting connection between said ,cross head and t V said bearing, i

' 11. In a self-laying track mechanism, a frame extending in the direction of propulsion of the mechanism, a track supporting wheel and a bear. ing therefor mounted at one end of said frame for movement" longitudinally thereof, a spring abutment mounted on saidframe inspacedrelai tion to said bearing-a coil spring seated'at one end on said abutment and extending longitudinally of said frame towardssaidbearing; a

plunger engagedby the other end of saidcoil spring, a first link pivoted on'said frame in the space between saidspring'abutment and said bearing, a cross head mounted on said frame for movementlongitudinally thereof in the space mechanism, a track'sup'portirig wheel and a hearing therefor mountedatone endof said frame for movement"longitudinally"thereof, a spring abutment mounted on said frame'in' spaced rela, tion to said bearing, a coil-spring seated at one end on said abutment and extending '1ongitu dinally of said'frame towards-said bearingfa plunger engaged by the other end of said coil spring, a first linlrm'ounted onsaid frame-for pivotalimovement about afirs't axis inthe space between said spring abutment and said bearing,

a cross head mounte'd'on' said frame for move- "ment longitudinallythereof-in'ithe space between "said first axis and said bearingya second link pivoted on Said CIOSS hQQ'd and connected with V said first link for pivotal movement "about 'a' second axis spaced from said first axis, a third linkpivotedon said-plungerand-connected with a'second link connecting said first linkwith said "cross head, a third link connecting said first link 7 10. In a self-layingtrack mechanism, a frame I said first: 1ink.-.- or:- iv ta mov ment. 2. about axis spaced-i mas idfirs ax as q e me??? han said econd; xis.,. si-i rth-r st ransmittin connection betwe n: id; os ad. nd a d bearing. q

13. In a: self-layir-rg;trackmechanism the combinatioxnw tn:a a n rama nd a r k 1. porting idler; Wheel 1 having. I a su orted on; said; frame-q o mo eme t. ni a ly' thereofn a ra r ea in ire ti n; iz r for; controlling-said; movement. of said; comprising a springcontrolled toggle: mechanism operatively connected to said; bearing-to resist said. movement; thereoi and having three pivot points; a firstsupported in-.fixedgpositio on said frame, a second-movable longltudinall t frame; and a thirdmovable transverselytofir said fr me.

, 14; In a-sel-f-la ying 'track;mechanism;. the com; inat r with a track rame n atraQk1 s.1- 1p porting idler wheel; having a bearing supported on said frame for movement longitudinallythere: of'in a trackreleasing direction, ofmeans; for

controlling. saidmovement :of said bearing. com

prisin a spring controlled toggle. mechanism having three .pivotpoints, a. first supported in fixed position on said frame; a, second;movable longitudinally of said frame and a. third positioned intermediate. the said first and second points and movable transversely of; saidframe, and thrust transmitting means operat-iyely, comnecting said second pivot point to saidhearing.

15. Ina seifdaying track; r, echanism, the combjnation with a track: frame, and a track supporting, idler wheel haying a bearing sunpm'ted on said frame for. movement: longitudinally thereof in a track releasing direction, of means for. controlling said movement of Sam -hearing comprising a spring controlleditoggle mechanism having three pivot points, a first supported in fixed-position on said frame, a secondmovable longitudinally of said frame, and a;third posi tinned intermediate the said first; and second points and movable transversely of; said frame,

jandga pair of thrust transmitting elementsg re,-

spectively. connectedtosaid :bearing to said itoggleimechanism atv saidisecondmivot pointkof thezlatter the said.thrust transmitting elements .being adiustably, connected to; each other; to

. permit adjustment, of the -axis {of said-{mien wheel "relative to the saidsecond pivot point.

* 18. In a self-laying trackmechanism, the co'm:

bina'tion with a track-frame, andra track sup: porting idler wheelzhaving, a bearing supported on-said frameior moveinent ina 'track-releasr I ing direction,- of meaus i011 controlling, said movement of said-bearing comprisinga spring controlledztoggle mechanism-i operatively; 0on nected to said bearingto resist,-said-='movement thereof and having-five pivot pqints,a-firstisupported in fixed position on said; frame, a; second movable .longitudinally --of said" frame,; afthird positioned intermediate said; first and, seQQDd .points and movable transversely of said-frame,

.afourth movable longitudinally ofsaid frame,

and a fifth positioned i intermedi'ate the said: firs and: fourth points and mbvfihlatransversely of saidsframe. V a

1'7: In a self-laying track mechanism, a track frame, a track supporting wheelimovable l'ongh tudinally of said frameintrack tensioningjand track releasing directions; anarm pivotedon said frame, connecting. meanswbetween said wheell-and: arm "operable to swingsaidarmy-in one direction byssaid traclg releasing-movement eali n ect rhe ween a'd e. iEln r }?1r leri ie ;t .z nd d; tm. b e.tq develone nm es ire rmcreasinann haniealadya i a qa arms aida k e easins-= qvementi i: ai -wh ff ct v to duc i e es stance fl a qi si ient ment a a ns ai r :2 .e ne mqv men :01 aid h e -1,.-. ,i 1 1 n' lfa ngi j rac pmechani m a r k r me. a "t ac isu ponns he mova on itudinally-of, ;-said frame; in. itrack'g tensioning and rap el asing, ire ti n-an. rms ivo 2 on i a c nne t ns me nsbet e n sa d whe and operable to swing said arm in one diection I i r k. el si mo eme f aid :w eela d. toe-m ver drwhe i aid. tr ensieni ir c i n. by .j in move nt of saidarm in the opposite direction, a resilient lement, ndfionnee insm ansbe ween i i i ent e ement adr aiqr rm. perab e. to. si n a d. esilie element by. a ins a mo ment of said am}; ,in said one ,direction and to in s i rmzt r a p te d ectio -by h e t 0n.-: id; r si ie eme t. ach of i o n ti m a s. om ri ng.- n e t ui e 0n. ai fl mmei en. e i roqat emoveme elat fYe; thereto. .in a;dil7ection transversely of the pivot. s ri i n rand=- nk conn ti etweenl ai z i s iptesz b e lem nt and s a erable te lo a ro es iv y ncrea n mechan al dv ntaseduring: ai .t k: l sinsnmoveme t :pfxwid whee fi ct ve duce e resistance; of said. resilient; element -against track;-releasing movement of ;-said wheeL; 1'9.;-In a selfgrlayinggtrackzmechanism: a track frames a -.track supporting wheel movable, longiudinal y f; s id" if amerin track; tensioning; and

track releasing. directions, anjarmthpivoted-qon sa d frame, a, resilient element," connecting meansz etween rsaid resilient; element: and said arm :operableto. tension said resilient element -by,swinging.movement of said;,arm in onemdirection, and a to swing; said arm .in the vopposite direction .-by,j the reaction" oiisaidmesilient ele- -ment,-ian: element. guided on said ;frame for, re,- ciprocating movement. relative.. thereto trans.- versely ofjthezpivot axis ofysaid'rarm; connecting means between. said wheel. andjsaid reciprocable element operableto move theJatterin one. di-

c o yi said; track;- releasing; moyeme t said wheel; and ito-;move ;said :wheel :in ,said track tensioning directiQl'lgby movement 0f said re.- ci-procable; element in its opposite 1 direction, and a;- link having-relatively. spaced zpivots centers :on said ;re ciprocab le s element; and: on .said; arm; re;- eotivels andvcpop ra in s i h. h a er o develop a progressively increasing; mechanical ,advantageiduring said :traclr, releasing movement of; sa d wheel; efiective; to reduce; the; resistance iii-said resilientelement against; said track reeasin gm veme tz qfgsaid jwheeli. V

nzar e r a i-ns ack mechanis -at track flame; tra k: suppo tin whea rmovable lonsi'- tudinally of said frame in track tensioning and track releasing directions, an arm pivoted on said frame, connecting means between said wheel and arm operable to swing said arm in one direction by said track releasing movement of said wheel and to move said wheel in said track tensioning direction by swinging movement of a said arm in the opposite direction, a resilient element, an element guided on said frame for movement relative thereto in opposite directions transversely of the pivot axis of said arm and cooperating with said resilient element to tenrection, a resilient element, and a mechanism 1 connecting said wheel with said resilient element operable to develop a progressively increasing mechanical advantage during said track releasing movement of said wheel, effective to reduce the resistance of said resilient element against said trackreleasing movement ofjsaid wheel, said mechanism comprising a pivoted arm, means connecting said arm with said resilient element for tensioning the latter by swinging movement of said arm in one direction,

a stop for limiting swinging movement of said arm in the opposite direction, and connecting means between said wheel and arm including a pair of relatively adjustable elements operable to adjust said wheel relative to said arm while the latter remains stationary in the limiting position thereof determined by said stop.

7 22. In a self-laying track mechanism, a track frame, a track supporting wheel movable longitudinally of said frame in a track releasing direction, a resilient element, and a mechanism connecting said wheel with said resilient element 013- erable to develop a progressively increasing mechanical advantage during said track releasing movement of said wheel, effective to reduce the resistance of said resilient element against said track releasing movement of said, wheel, said mechanism comprising an arm pivoted on said frame, means connecting said arm with said resilient element for tensioning the latter by swin ing movement of said arm in one direction, a stop on said frame engageable by said arm for limiting swinging movement of said arm in the 0pposite direction, and connecting means between said wheel and arm including a pair of relatively adjustable elements operable to adjust said wheel relative to said arm while the latter remains sta-,

tionary in the limiting position thereof determined by said stop.

23. In a self-laying track mechanism, a track frame, a track supporting wheel movable longitudinally of said frame in a track releasing direction, a resilient element, and a mechanism connecting said wheel with said resilient element operable to develop a progressively increasing mechanical advantage during said track releasing movement of said wheel, effective to reduce the resistance of said resilient element againstsaid track releasing movement of said wheel, said mechanism comprising an arm pivoted 'on said frame, .means connectingsaid arm with said re-. silient element for tensioning the latter by swinging movement of said arm in one direction, a

stop on said frame for limitin swinging movement of said arm in thev opposite direction, an

element guided on said frame for reciprocating movement relative thereto, a linkhavingrelatively spaced pivot centers on said arm and're ciprocable element, respectively, and a pair of relatively adjustable elements cooperating, re-

spectively, with said wheel and with said reciprocable element operable to adjust said wheel relative to the'latter. v

24. A self-laying track mechanism comprising a track frame, a track supporting wheel movable on said frame in a track releasing direction, a first reciprocable element guided on said frame and having a thrust connection with said wheel, for transmitting track releasing movement of said wheel to said first'reciprocable element, an arm pivoted on said frame, a link pivoted on said arm and having a pivotalthrust connection with said first reciprocable element for transmitting track releasing movement of said wheel to said arm, a second reciprocableielement'guided on I said frame, another link pivoted on said arm and having a pivotal thrust connection with said' second reciprocable element for transmitting track releasing movement of said wheel to said second reciprocable element, and resilient means cooperating with said second reciprocable element to yieldingly resist said track releasing movement of said wheel;

2 A self-laying track mechanism as defined in claim 24,,in which at least one of said pivotal thrust connections comprises a socket and a thrust element bearing upon eachother in thrust transmitting direction, said socket and thrust element being freely separable from each other I in the opposite direction. a

26. A self-laying track mechanism comprising,

a track frame, a track supporting wheel movj able on said trackframe in a track releasing direction, a first reciprocable element guided on said frame and having a thrust connection with said wheel for transmitting track releasing movement of said wheel to said first reciprocable element, a second reciprocable element guided on said frame, toggle mechanism for transmitting track releasing movement of said wheel from said first to said second reciprocableelement, comprising an arm pivoted on said frame, a link pivoted on said arm and having a thrust connec -I tion with said first reciprocable element, another link pivoted on said arm and having a thrust con- ,nection with said second reciprocable element;

resilient means cooperatingwith saidsecond reciprocable element to yieldingly resist track re-r leasing movement of said wheel; and control means for said toggle mechanism and said resilient means, including a stop on said frame engageable by one of said reciprocable elements,

A self-laying track mechanism as defined it in claim 26, m1 which'the control means for said toggle mechanism and said resilient means includes a stop on said frame engageable by said second reciprocable element.

28. A self-laying track mechanism as-defined in claim 26, in which said thrust connection between said first reciprocable element and said wheel comprises a pair of thrust transmitting elea ments extensibly adjustable relative to each other. 1 I I EMIL ninoanmus. 

